Vertical patch drying

ABSTRACT

Apparatus is provided, including one or more drug patches ( 20 ) and a surface ( 22 ) configured to hold the one or more drug patches. A housing ( 24 ) is shaped to define one or more gas inflow openings ( 30 ) that are configured to facilitate drying of the patches by directing a flow of a gas toward the patches, a midline of the flow being at an angle of less than  20  degrees from a normal to the surface. Other embodiments are also described.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication 61/001,016 to Bar-El et al., filed Oct. 29, 2007, entitled,“Vertical patch drying,” which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to medical apparatus andmethods. Specifically, the present invention relates to dissolvable drugpatches.

BACKGROUND OF THE INVENTION

In recent years many drugs have been formulated for transdermaldelivery. Transdermal delivery of drugs is the favored delivery methodfor many patients, particularly for those who find it difficult to havedrugs administered to them orally or via an injection.

US Patent Application Publication 2004/0137044 to Stern et al., which isincorporated herein by reference, describes a system for transdermaldelivery of dried or lyophilized pharmaceutical compositions and methodsfor using the system. The system comprises an apparatus for facilitatingtransdermal delivery of an agent that generates hydrophilicmicro-channels, and a patch comprising a therapeutically active agent.The system is described as being useful for transdermal delivery ofhydrophilic agents, particularly of high molecular weight proteins.

U.S. Pat. No. 5,983,135 to Avrahami, which is incorporated herein byreference, describes a device for delivery of a powder to the skin of asubject which includes a pad, made of an insulating material and havingan upper side and a lower side, which lower side is placed against theskin after application of the powder thereto. An electrical power sourceapplies an electrical potential to the pad, causing the powder to adhereby electrostatic force to the lower side of the pad, and then alters thepotential so that the powder is released from the pad and contacts theskin against which the pad is placed.

U.S. Pat. No. 7,097,850 to Chappa et al., relevant portions of which areincorporated herein by reference, describes a coating composition in theform of a one or multi-part system, and method of applying such acomposition under conditions of controlled humidity, for use in coatingdevice surfaces to control and/or improve their ability to releasebioactive agents in aqueous systems. The coating composition isparticularly adapted for use with medical devices that undergosignificant flexion and/or expansion in the course of their deliveryand/or use, such as stents and catheters. The composition includes thebioactive agent in combination with a first polymer component such aspolyalkyl(meth)acrylate, polyaryl(meth)acrylate,polyaralkyl(meth)acrylate, or polyaryloxyalkyl(meth)acrylate and asecond polymer component such as poly(ethylene-co-vinyl acetate).

U.S. Pat. No. 6,932,983 to Straub et al., relevant portions of which areincorporated herein by reference, describes drugs, especially lowaqueous solubility drugs, which are provided in a porous matrix form,preferably microparticles, which enhances dissolution of the drug inaqueous media. The drug matrices preferably are made using a processthat includes (i) dissolving a drug, preferably a drug having lowaqueous solubility, in a volatile solvent to form a drug solution, (ii)combining at least one pore forming agent with the drug solution to forman emulsion, suspension, or second solution, and (iii) removing thevolatile solvent and pore forming agent from the emulsion, suspension,or second solution to yield the porous matrix of drug. The pore formingagent can be either a volatile liquid that is immiscible with the drugsolvent or a volatile solid compound, preferably a volatile salt. In apreferred embodiment, spray drying is used to remove the solvents andthe pore forming agent. The resulting porous matrix is described ashaving a faster rate of dissolution following administration to apatient, as compared to non-porous matrix forms of the drug. In apreferred embodiment, microparticles of the porous drug matrix arereconstituted with an aqueous medium and administered parenterally, orprocessed using standard techniques into tablets or capsules for oraladministration.

Alza Corporation (CA, USA) has developed “Macroflux®” products, whichare described as incorporating a thin titanium screen with precisionmicroprojections which, when applied to the skin, create superficialpathways through the skin's dead barrier layer allowing transport ofmacromolecules. Macroflux® products provide the option of dry-coatingthe drug on the Macroflux® microprojection array for bolus delivery intothe skin or using a drug reservoir for continuous passive orelectrotransport applications. In addition, the creation of Macroflux®pathways is described as allowing for better control of drugdistribution throughout the skin patch treatment area and reduction inpotential skin irritation.

The following patents and patent applications, relevant portions ofwhich are incorporated herein by reference, may be of interest:

U.S. Pat. No. 6,855,372 to Trautman et al.

US Patent Application Publication 2004/0059282 to Flock et al.

U.S. Pat. No. 5,685,837 to Horstmann

U.S. Pat. No. 5,230,898 to Horstmann et al.

U.S. Pat. No. 6,522,918 to Crisp et al.

U.S. Pat. No. 6,374,136 to Murdock

U.S. Pat. No. 6,251,100 to Flock et al.

US Patent Application Publication 2003/0204163 to Marchitto et al.

U.S. Pat. No. 5,141,750 to Lee et al.

U.S. Pat. No. 6,248,349 to Suzuki et al.

PCT Publication WO 05/088299 to Tsuji et al.

The following references, relevant portions of which are incorporatedherein by reference, may be of interest:

Patel et al., “Fast Dissolving Drug Delivery Systems: An Update,”Pharmainfo.net (July 2006)

Holman J P, “Heat Transfer,” McGraw-Hill Inc., USA (1976)

SUMMARY OF THE INVENTION

In some embodiments of the present invention, a drug, in liquid form, isapplied to a patch. The patch is then placed, substantially flat, on asurface, and is dried by normal flow drying, i.e., a flow of gas isdirected toward the patch, the midline of the flow being at an angle ofless than 20 degrees from the normal to the surface, e.g., less than 10degrees.

In some embodiments, for a given amount of gas, normal flow dryingallows for the patches to be dried at a greater rate than if the patcheswere dried by directing a flow of gas toward the patches the midline ofwhich flow is at an angle of greater than 20 degrees from a normal tothe surface, i.e. by non-normal flow drying. (Nevertheless, it may bethat for some applications, normal flow drying dries the patches at arate that is equal to, or lower than, if the patches were dried bynon-normal flow drying.) Typically, drying the patch using normal flowdrying uses less gas than is used for non-normal flow drying.(Nevertheless, it may be that for some applications, an equal or greateramount of gas is used for the normal flow drying.) In some embodiments,normal flow drying reduces a chance of a patch being displaced from itsposition on the surface.

Typically, air, and/or an inert gas, is directed through openings towardthe patches. In some embodiments, the openings are shaped to definenozzles, and jets of gas are directed toward the patches.

In some applications, the humidity of the gas which is directed towardthe patches is controlled. The humidity of the gas with which thepatches are dried may have an effect on the ultimate dissolutionproperties of the drug when the patch is placed on the moistened skin ofa user. Alternatively or additionally, the humidity of the gas iscontrolled for a different reason, e.g., lower humidity increases therate of drying.

In some embodiments, an array of patches are placed on the surface andan array of jets direct the gas toward the array of patches. In someapplications, the array of patches is stationary and is disposed insidea chamber during the drying of the patches. A jet of gas is directedtoward each respective patch of the array. Alternatively, the array ofpatches is moved through the chamber during the drying. For example, thesurface may comprise a conveyor belt. The patches are placed on theconveyor belt and the conveyor belt moves the patches through the dryingchamber during the drying. In some embodiments, the surface moves duringthe drying and the jets are configured to direct the gas toward thepatches only when the patches are disposed underneath respective jets.

In some embodiments, the openings do not define nozzles, or the openingsdefine nozzles but the nozzles do not direct jets toward respectivepatches. In accordance with these embodiments, the gas is directed inthe direction of the patches, but not toward individual patches. Forexample, the gas may be directed toward the patches by passing highpressure air through holes in a surface.

There is therefore provided in accordance with an embodiment of theinvention, apparatus, including:

one or more drug patches;

a surface configured to hold the one or more drug patches; and

a housing shaped to define one or more gas inflow openings that areconfigured to facilitate drying of the patches by directing a flow of agas toward the patches, a midline of the flow being at an angle of lessthan 20 degrees from a normal to the surface.

In an embodiment, the gas includes room air and the one or more gasinflow openings are configured to direct the air toward the patches.

In an embodiment, the gas consists essentially of an inert gas and theone or more gas inflow openings are configured to direct the inert gastoward the patches.

In an embodiment, the housing is shaped to define the one or moreopenings as one or more nozzles configured to dry the patches bydirecting jets of the gas toward the patches, midlines of the respectivejets of gas being at an angle of less than 20 degrees from the normal.

In an embodiment, the apparatus includes a pressure source configured topump the gas through the openings at a speed of between 3 m/s and 15m/s.

In an embodiment, the pressure source is configured to pump the gasthrough the openings at a speed of between 6 m/s and 12 m/s.

In an embodiment, the openings have diameters that are between 0.5 mmand 7 mm.

In an embodiment, the openings have diameters that are between 2 mm and5 mm.

In an embodiment, the openings are configured to direct the gas towardthe patches from a distance of between 0.5 cm and 7 cm from the patches.

In an embodiment, the openings are configured to direct the gas towardthe patches from a distance of between 2 cm and 5 cm from the patches.

In an embodiment, the apparatus includes a humidity controllerconfigured to control a humidity of the gas.

In an embodiment, the humidity controller is configured to maintain thehumidity of the gas between 2% and 20% relative humidity during dryingof the one or more drug patches.

In an embodiment, the humidity controller is configured to maintain thehumidity of the gas between 5% and 10% relative humidity during dryingof the one or more drug patches.

In an embodiment, the apparatus includes a humidity detector configuredto detect a humidity of the gas.

In an embodiment, the apparatus includes a control unit configured tomodulate the humidity of the gas in response to the detected humidity.

In an embodiment, the one or more drug patches include an array of drugpatches, the surface is configured to hold the array of patches, and thegas inflow openings are configured to dry the array of patches.

In an embodiment, the surface is configured to be stationary duringdrying of the patches.

In an embodiment, the surface is configured to move the array of patchesduring drying of the patches.

In an embodiment, the gas inflow openings are arranged to define anarray of nozzles configured to dry the patches by directing a respectivejet of the gas toward each patch, midlines of the respective jets beingat an angle of less than 20 degrees from a normal to the surface.

In an embodiment, the number of patches in the array of patches is equalin number to the number of nozzles in the array of nozzles.

In an embodiment, each nozzle is disposed so as to direct the gas towarda respective one of the patches.

In an embodiment, the surface is configured to move the array of patchesintermittently, and the nozzles are configured to direct the gas duringperiods between the intermittent moving of the array.

There is further provided, in accordance with an embodiment of thepresent invention, a method for preparing a drug patch, including:

applying a drug in liquid form to a patch;

placing the patch on a surface; and

drying the patch by directing a flow of a gas toward the patch, amidline of the flow being at an angle of less than 20 degrees from anormal to the surface.

In an embodiment, the method further includes controlling a humidity ofthe gas.

In an embodiment, the gas includes room air, directing the flow of thegas toward the patch includes directing the air toward the patch, andcontrolling the humidity of the gas includes controlling a humidity ofthe air.

In an embodiment, the gas consists essentially of an inert gas,directing the flow of the gas toward the patch includes directing theinert gas toward the patch, and controlling the humidity of the gasincludes controlling a humidity of the inert gas.

The present invention will be more fully understood from the followingdetailed description of embodiments thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an array of drug patches beingdried, in accordance with an embodiment of the invention;

FIG. 2 is a schematic illustration of a moving array of drug patchesbeing dried by jets, in accordance with an embodiment of the invention;and

FIG. 3 is a schematic illustration of a moving array of drug patchesbeing dried, in accordance with another embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIG. 1, which is a schematic illustration of anarray of drug patches 20, being dried in accordance with an embodimentof the invention. The drug patches are arranged on a surface 22, whichis placed inside a drying chamber 24 and remains stationary during thedrying. In some embodiments, the opening of the drying chamber iscovered with a cover 26 during the drying. A pressure source 28 pumps agas out of an array of openings 30, the openings being configured todirect a flow of the gas toward the patches, the midline of the flowbeing at an angle of less than 20 degrees from the normal to thesurface. (The angles shown in FIG. 1 are substantially zero degrees fromthe normal.) Typically, the gas comprises air and/or an inert gas. Insome embodiments, each opening directs the gas toward a respectivepatch, as shown in FIG. 1.

In some embodiments, the humidity of the gas with which the patches aredried is controlled. Typically, as shown in FIG. 1, the gas passesthrough a humidity controller 36. Typically, the humidity controller isconfigured to maintain the humidity of the gas between 2% and 20%relative humidity. In some embodiments, the controller maintains thehumidity between 5% and 10% relative humidity. For some applications, ahumidity detector 32 detects the humidity of the gas, or the humidity ofthe environment in which the patches are dried, for example, the room orthe drying chamber in which the patches are dried. A control unit 34regulates the humidity of the gas, via the humidity controller, inresponse to the detected humidity.

Experiments are described hereinbelow that evaluated the dissolutionproperties of patches dried in controlled environments with respectiverelative humidity levels. It was observed by the inventors that dryingthe patches in conditions of lower relative humidity results in patcheshaving substantially superior dissolution properties. Subsequently,experiments were conducted by the inventors, in which the humidity ofthe gas which was used to dry the patches was controlled. It wasobserved that patches dried with a gas having a relative humidity ofbetween 5% and 10% had good dissolution properties.

Reference is now made to FIG. 2, which is a schematic illustration of anarray of drug patches 20 being dried, in accordance with an embodimentof the invention. Although only one row of patches is shown, in someembodiments the array comprises a plurality of rows. The patches areconfigured to move inside the drying chamber, arranged in an array onsurface 22. For example, surface 22 may comprise the surface of aconveyor belt. Prior to the drying, the patches are arranged in an arrayon the surface, and the surface then moves inside the drying chamber.The direction of motion of the surface is indicated by arrow 50.

In some embodiments, the openings are shaped to define nozzles, as shownin FIG. 2. Typically, the nozzles are pneumatic adjustable valves, forexample, those manufactured by Pisco Pneumatic Equipments LTD (model no.JNC4-01). The nozzles are configured to direct jets of gas towardrespective patches, during the drying of the patches. In someembodiments, surface 22 remains stationary during the drying of thepatches. Alternatively, surface 22 moves through the chamber during thedrying, and the jets are configured to direct the gas toward the patchesonly when each patch is aligned with a respective jet. The patches aremoved out of the drying chamber, subsequent to the drying, in thedirection of arrow 50.

Reference is now made to FIG. 3, which is a schematic illustration of anarray of drug patches 20 being dried, in accordance with an embodimentof the invention. The patches are arranged on surface 22 which moves inthe direction of arrow 50 during the drying of the patches. Althoughonly one row of patches is shown, in some embodiments the arraycomprises a plurality of rows. The inner, upper surface of dryingchamber 24 is shaped to define openings 30 which direct respective flowsof gas into the drying chamber and toward the patches, the midline ofthe respective gas flows being at an angle that is less than 20 degreesfrom the normal to the surface. Typically, the gas is directed towardthe patches at a speed of between 3 m/s and 15 m/s, e.g., between 6 m/sand 12 m/s. The openings direct the gas in the direction of the patches,but not toward individual patches. In such embodiments, there is overlapof the gas flow coming out of adjacent nozzles. Typically, a divergencealpha from a midline 52 of each of the jets is between 10 degrees and 30degrees, e.g. between 15 degrees and 25 degrees. Openings 30 typicallyhave a diameter of between 0.5 mm and 7 mm, e.g., between 2 mm and 5 mm.Distance D1, from the openings to the patches is typically between 0.5cm and 7 cm, e.g., between 2 cm and 5 cm.

In some embodiments, the patches are arranged on surface 22, and surface22 moves through the drying chamber in a continuous, assembly-line-likefashion. Control unit 34 is configured to control the movement of thesurface and the directing of the gas through the openings. For someapplications, the control unit is configured to control the movement ofthe surface or the directing of the gas responsively to the humiditydetected by humidity detector 32.

Experiments were conducted to investigate the effect of the humidity ofthe environment in which drug patches are dried on their ultimatedissolution properties. Patches were printed with 50 micrograms ofhPTH(1-34) (human parathyroid hormone) by applying a 10 mg/ml hPTHsolution to each patch. Patches were dried at 25 C for 3 hours in aclimatic chamber under two relative humidity levels:

1. Five patches were dried at 84% relative humidity controlledconditions.

2. Five patches were dried at 45% relative humidity controlledconditions.

Following 3 hours drying inside the climatic chamber, the patches werepacked in a pouch filled with argon gas and containing a silica gelsachet, and transferred into a room held at 4 C.

A third group of five patches was dried at 25 C under conditions ofapproximately 1.5% relative humidity. Such conditions were created byplacing the patches inside sealed laminated pouches with silica gelimmediately after the printing of the patches.

The dissolution properties of the patches were analyzed after 3 days andafter 7 days, using trifluoroacetic acid/high performance liquidchromatography (TFA-HPLC) analysis. The results are presented in Table1.

TABLE 1 Dissolution results for hPTH drug patches dried in conditions ofcontrolled humidity hPTH release (% of quantity initially dried onto thepatch) Conditions 3 Days 7 Days 84% RH/25 C. 55.9 ± 7.6 55.3 ± 4.5 45%RH/25 C. 89.4 ± 2.8 88.2 ± 1.9 ~1.5% RH/25 C.   88.3 ± 1.1 90.8 ± 1.9 (±indicates standard deviation)

The results indicate that drying the patches in conditions of lowerrelative humidity results in patches having improved dissolutionproperties.

A further experiment was conducted, in which a batch of 24 patches wasprinted with 90 micrograms of hPTH(1-34). The patches were dried usingdrying techniques that are known in the art, in an environment having acontrolled humidity of between 30% RH/25 C and 45% RH/25 C. The dryingtime of the patches was measured and the patches were found to havedrying times of between 30 and 50 minutes. The dissolution properties offive of the patches were analyzed after the patches had been stored inpouches containing a silica gel sachet, inside a room at 4 C for oneweek. The patches released a mean of 85.1%±3.5% of the quantity ofhPTH(1-34) that was initially dried onto the respective patches. Thedissolution properties of five of the remaining patches of the batch ofpatches were analyzed after the remaining patches had been stored inpouches containing a silica gel sachet, inside a room at 4 C for onemonth. The patches released a mean of 83.0%±4.1% of the quantity ofhPTH(1-34) that was initially dried onto the respective patches.

In still further experiments, the inventors analyzed 50 patches thatwere dried using normal flow drying techniques, as describedhereinabove. The patches that were analyzed were hPTH(1-34) patches,having either 50 micrograms or 80 micrograms of the drug dried ontothem. The patches were dried with dried air having a relative humidityof between 5% RH/25 C and 10% RH/25 C. The mean drying time of thepatches under these conditions was less than 4 minutes. All of thepatches released between 80% and 90% of the quantity of hPTH(1-34) thatwas initially dried onto the respective patches. In addition, thepatches were found to release less than 5% degradation products, as werepatches dried by the alternative methods described above with referenceto the other experiments. These results indicated to the inventors thatdrying patches using normal flow drying, and using dried air, producespatches having suitable dissolution properties in a relatively shorttime.

In an embodiment of the invention, a row of patches passes through adrying chamber on a conveyor belt which is continually operated as partof a drug patch manufacturing line. Dried air having a humidity ofbetween 5% RH/25 C and 10% RH/25 C is directed toward the conveyor beltwith normal flow. Under these conditions, each of the patches dries inapproximately four minutes (actual time being dependent on a number offactors). In an embodiment, the conveyor belt moves with a speed of 1m/minute and the conveyor belt is 4 meters long. Round patches having adiameter of 2 cm, or square patches having a length of 2 cm, arearranged on the conveyor belt such that there are 50 patches arrangedalong each meter of the conveyor belt. Each minute, 50 dry patches thathave been dried on the conveyor belt pass to the next stage of themanufacturing line. In some embodiments, more than one row of patchesare arranged on the conveyor belt, for example, four rows of patches maybe arranged adjacently on the conveyor belt, such that 200 patches aredried per minute.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

1. Apparatus, comprising: one or more drug patches; a surface configuredto hold the one or more drug patches; and a housing shaped to define oneor more gas inflow openings that are configured to facilitate drying ofthe patches by directing a flow of a gas toward the patches, a midlineof the flow being at an angle of less than 20 degrees from a normal tothe surface. 2-3. (canceled)
 4. The apparatus according to claim 1,wherein the housing is shaped to define the one or more openings as oneor more nozzles configured to dry the patches by directing jets of thegas toward the patches, midlines of the respective jets of gas being atan angle of less than 20 degrees from the normal.
 5. The apparatusaccording to claim 1, and comprising a pressure source configured topump the gas through the openings at a speed of between 3 m/s and 15m/s.
 6. (canceled)
 7. The apparatus according to claim 1, wherein theopenings have diameters that are between 0.5 mm and 7 mm.
 8. (canceled)9. The apparatus according to claim 1, wherein the openings areconfigured to direct the gas toward the patches from a distance ofbetween 0.5 cm and 7 cm from the patches.
 10. (canceled)
 11. Theapparatus according to claim 1, and comprising a humidity controllerconfigured to control a humidity of the gas.
 12. The apparatus accordingto claim 11, wherein the humidity controller is configured to maintainthe humidity of the gas between 2% and 20% relative humidity duringdrying of the one or more drug patches.
 13. The apparatus according toclaim 12, wherein the humidity controller is configured to maintain thehumidity of the gas between 5% and 10% relative humidity during dryingof the one or more drug patches.
 14. (canceled)
 15. The apparatusaccording to claim 1, further comprising a humidity detector configuredto detect a humidity of the gas, and a control unit configured tomodulate the humidity of the gas in response to the detected humidity.16. The apparatus according to claim 1, wherein the one or more drugpatches comprise an array of drug patches, wherein the surface isconfigured to hold the array of patches, and wherein the gas inflowopenings are configured to dry the array of patches.
 17. The apparatusaccording to claim 16, wherein the surface is configured to bestationary during drying of the patches.
 18. The apparatus according toclaim 16, wherein the surface is configured to move the array of patchesduring drying of the patches.
 19. The apparatus according to claim 16,wherein the gas inflow openings are arranged to define an array ofnozzles configured to dry the patches by directing a respective jet ofthe gas toward each patch, midlines of the respective jets being at anangle of less than 20 degrees from a normal to the surface.
 20. Theapparatus according to claim 19, wherein the number of patches in thearray of patches is equal in number to the number of nozzles in thearray of nozzles.
 21. (canceled)
 22. The apparatus according to claim19, wherein the surface is configured to move the array of patchesintermittently, and wherein the nozzles are configured to direct the gasduring periods between the intermittent moving of the array.
 23. Amethod for preparing a drug patch, comprising: applying a drug in liquidform to a patch; placing the patch on a surface; and drying the patch bydirecting a flow of a gas toward the patch, a midline of the flow beingat an angle of less than 20 degrees from a normal to the surface. 24.The method according to claim 23, wherein directing the flow of the gastoward the patch comprises directing a jet of gas toward the patch.25-26. (canceled)
 27. The method according to claim 23, whereindirecting the flow of the gas comprises directing the flow of the gasthrough an opening which has a diameter of between 0.5 mm and 7 mm. 28.(canceled)
 29. The method according to claim 23, wherein directing theflow of the gas comprises directing the flow of the gas through anopening that is at a distance of between 0.5 cm and 7 cm from the patch.30. (canceled)
 31. The method according to claim 23, wherein directingthe flow of the gas toward the patch comprises directing the flow of thegas toward the patch at a speed of between 3 m/s and 15 m/s. 32.(canceled)
 33. The method according to claim 23, further comprisingcontrolling a humidity of the gas. 34-35. (canceled)
 36. The methodaccording to claim 33, wherein controlling the humidity of the gascomprises maintaining the humidity of the gas at a level that is between2% and 20% relative humidity.
 37. The method according to claim 36,wherein controlling the humidity of the environment comprisesmaintaining the humidity of the gas at a level that is between 5% and10% relative humidity.
 38. (canceled)
 39. The method according to claim23, further comprising detecting a humidity of the gas, and modulatingthe humidity of the gas responsively to the detected humidity.
 40. Themethod according to claim 23, wherein the patch includes an array ofpatches, wherein placing the patch on the surface comprises placing thearray of patches on the surface, and wherein directing the flow of thegas toward the patch comprises directing the flow of the gas toward thearray of patches.
 41. The method according to claim 40, wherein dryingthe array of patches comprises drying the array while the array isstationary.
 42. The method according to claim 40, and comprising movingthe array of patches during the directing of the gas toward the array.43. The method according to claim 40, and comprising moving the arrayintermittently, wherein directing the flow of the gas comprisesdirecting the flow of the gas during periods between the intermittentmoving of the array.
 44. The method according to claim 40, whereindirecting the flow of the gas toward the array of patches comprisesdirecting a jet of gas toward each respective patch of the array.